The following prior art United States patents are all directed to edging systems for edging roofs.
______________________________________ U.S. Pat. No. Issue Date Title ______________________________________ 3,405,485 10/15/68 Flashing Systems for Flat Roofs 3,503,162 3/31/70 Combination Water Cant, Sealer Strip & Fascia 3,533,201 10/13/70 Fascia and Flashing Construction 3,585,766 6/22/71 Flashing Construction 3,738,068 6/12/73 Conjoint Fascia and Water Dam 3,992,827 11/23/76 Coping Assembly with Deformable Seal Clamp 4,067,152 1/10/78 Fascia Compression Clip 4,071,987 2/7/78 Gravel Stop 4,241,549 12/30/80 Conjoint Fascia, Flashing and Water Dam ______________________________________
Also, the following specification sheets are currently circulated for commercially available edging systems.
______________________________________ Company Title ______________________________________ Architectural Products Co. Fascia System Type TE and Galvanized Water Dam W. P. Hickman Co., Inc. Econosnap Extruded Roof Edge System FM Research Corporation Drip-Proof Fascia and Cant Dam Systems ______________________________________
With respect to the above art, U.S. Pat. No. 3,405,485 discloses a roof flashing system for use with tar coated roofs. This system is expensive to manufacture and install, requiring a large number of relatively complicated parts, including two wooden supports that must be accurately cut and then installed.
U.S. Pat. No. 3,503,162 discloses a combination water dam, sealer strip and fascia edge structure for a flat roof having a built-up roofing material with a plurality of roofing plies. The sealer strip is secured with machine screws which are time consuming for the roofers to install, and which penetrate the roofing material, allowing water leakage around the screw holes as the screws loosen or the washers deteriorate. This system would not be satisfactory for use with a single ply membrane, due to leakage problems aggravated by tearing of the membrane around the screws due to contraction and expansion of the membrane with temperature changes in the weather.
U.S. Pat. No. 3,533,201 discloses a system for built-up roofs that has the same disadvantages as the system described in U.S. Pat. No. 3,503,162.
U.S. Pat. No. 3,585,766 discloses another system for use with built-up roofs only. This system uses a relatively large number of components including a wooden support that must be cut to shape, resulting in excessive manufacturing expense and installation cost. This system could not be used with a single ply membrane in any event, since the sharp edges of the cant would cut the membrane.
U.S. Pat. No. 3,738,068 utilizes a conjoint fascia and water dam. The system is relatively complicated, and both the fascia and water dam must be made by an extrusion process, a much more expensive process than the forming of the components from metal sheets. Also, extruded metal components cannot be prepainted, whereas metal sheets can be prepainted prior to the forming operation. The system also requires the use of machine screws through the fascia to fasten the system in place, a time consuming procedure for the roofer and an extra complication and expense in threading the holes for the screws in the manufacture of the fascia.
U.S. Pat. No. 3,992,827 is an edging system for roofs having parapet walls, i.e. the system cannot be used with flat roofs.
U.S. Pat. No. 4,067,152 discloses an edging system using a fascia compression clip. The fascia must be manufactured by extrusion, a much more expensive process than forming the fascia from sheet metal. The fascia clip has a deformable junction that is necessarily thin and hence relatively weak. The roofing membrane does not go over the top of the cant, so that water build-up and leakage under the compression clip could result in leakage under the membrane, causing rotting of the roof substructure. Also, the fascia clips are made into two foot sections with notches between, allowing rain water to accumulate under the fascia clips, markedly increasing the chance of metal corrosion. In addition, this system requires an extra sheet of material on the surface of the cant to block water penetration, an extra expense in manufacture and installation.
U.S. Pat. No. 4,071,987 discloses a roof edging system having a fascia member and a spring cant between which a roofing membrane is compressed. However, the top of the spring cant has sharp edges at the compression points, subjecting the membrane to possible severing during installation of the system or from wear due to expansion and contraction of both the metal components and the membrane itself. In addition, the membrane is bent 180.degree. in the compression area, accelerating penetration and causing cracking of the membrane with aging. Also, this system requires either (a) the use of adhesive to secure the spring cant to the top edge of the building, a time consuming and messy procedure, and requires the spring cant to be formed with numerous holes through which the adhesive may penetrate to assist in holding the cant to the roof, or (b) the spring cant may be fastened to the top of the roof with nailing "fingers", a relatively expensive manufacturing operation. A further problem with this system is that, due to the varied thickness of roofing membranes, the top edge of the fascia must be fabricated for a particular thickness of membrane, reducing the versatility of the system for use with other thicknesses of roofing membranes. If used inadvertently with, e.g. a thinner membrane, water will become trapped between the fascia and the cant, causing accelerated corrosion problems. Furthermore, if pressure is applied to the slope of the cant, such as by a maintenance worker inadvertently stepping on the cant, the fascia will probably become disengaged from the cant.
U.S. Pat. No. 4,241,549 is directed to conjoint fascia, flashing and water dam. This system suffers from many of the disadvantages inherent in that disclosed in U.S. Pat. No. 4,071,987 above, i.e. the membrane is bent at a 180.degree. angle, and the lack of versatility of the system for differing membrane thicknesses. Also, the fascia edge has a lower flashing lip, resulting in a sharp edge pressing against the membrane, which will abrade and eventually penetrate the membrane on contraction and expansion of the metal fascia.
Architectural Products Co. Specification Sheet - this system utilizes a fascia and a water dam (cant) wherein the roofing membrane is bent at a 180.degree. angle over the sharp edges of the top of the cant, permitting severing of the membrane on installation or after contraction and expansion of the membrane and the metal components. Also, the fascia is formed by extrusion, an expensive process. Furthermore, the inward lip of the fascia exposes the locking mechanism to wind pressures that in severe storms could result in disconnecting of the fascia from the cant. In addition, stones and debris can lodge under the fascia lip, resulting in accelerated wearing of the membrane upon expansion and contraction of the metal components and membrane.
W. P. Hickman Co. Specification Sheet - this system is based on the disclosure of U.S. Pat. No. 4,071,987, discussed above. In addition, the spring clip is formed with a sharp edge that presses against the membrane, with wear and penetration liability that exists on installation and during use. In the event the membrane is cut, water can seep inside the spring clips, causing their erosion. Furthermore, this system requires the separate nailing of the membrane to the outside section of the roof, which is time consuming on installation. Also, the fascia member is extruded, an expensive process. A further disadvantage of this system is that the spring clip has an "open" design, which is not very strong structurally, and which may result in the spring clip being bent out of shape during its installation. Additionally, in the event the roofing membrane is ripped, wind under the ripped membrane may cause enough pressure on the system to uncouple the fascia from the cant. Furthermore, if pressure is applied to the slope of the cant, the fascia will probably become disengaged from the cant.
FM Research Corporation Specification Sheet - this system appears to be that disclosed in U.S. Pat. No. 3,738,068, and the comments relating to that patent are equally applicable to the system shown in this flyer.